Rationalizing the formation of binary mixed thiol self-assembled monolayers

Abstract

International audiencePeriodic DFT-D calculations are used to decipher the role of intermolecular forces on the stability of mixed linear thiol self-assembled monolayers (SAMs) on Au(111) and compared with experiment. The interaction energy is rationalized by quantifying its different contributions. The inter-chain interaction energy is shown to be in direct relation with the surface reconstruction and the formation of adatoms. The stability of the mixed SAM systems is predicted by calculations and validated with experiments. In order to describe predictively the segregation of binary thiol mixtures adsorption on Au surfaces a segregation descriptor is defined. This procedure is a promising step forward in the prediction of segregated SAMs leading to future functional nanomaterials, including Janus or patchy nanoparticles for optics, formulation and self-assembled patterns

Alkyl-Modified Gold Surfaces: Characterization of the Au–C Bond

“…In the literature, the binding energy of alkylthiols varies from −25 kcal/mol for conjugated molecules to −44 kcal/mol depending on the length and the chemical structure. 41,42 The above values can also be compared with that calculated (with two different methods) for Au− C(aryl) bonds obtained by grafting diazonium salts on gold: −34.4 kcal/mol (Au19−C 6 H 5 ) 12 and −24.0 kcal/mol [Au(111), TOP site]−C 6 H 5 . 23 These calculations indicate that the energy of Au(111)−C(alkyl) bond is equivalent to that of an Au−C(aryl) bond; the Au(111)−S−alkyl bond is more stable than the Au(111)−C(alkyl) one by −8.6 kcal/mol.…”

“…In the literature, the binding energy of alkylthiols varies from −25 kcal/mol for conjugated molecules to −44 kcal/mol depending on the length and the chemical structure. 41,42 The above values can also be compared and there is no apparent pulling of gold atoms from the surface. Considering the above computed bond energies that indicate a significant difference of ∼−8.6 kcal/mol between the two grafted molecules, one should, in principle, be able to replace reversibly the bonded moiety.…”

Effect of chemical surface modification on dendritic gold in surface‐enhanced Raman scattering‐active substrates

“…Phenyl mercaptans with different terminal functional groups, including 4‐mercaptophenol, 4‐aminothiophenol, 4‐methylthiophenol, and thiophenol, can be used to investigate the effect of the chemical environment on SERS. The phenyl thiol in the aqueous solution was directly chemisorbed onto the Au‐D surface with a thiol functional group . After surface modification, the Au‐Ds can retain the nanostructures and morphology (Figure ).…”

Nanoparticle Assembling through Click Chemistry Directed by Mixed SAMs for Magnetic Applications

“…Indeed, the dispersion interactions represent 60% (eq ) of the total adsorption energy, and 30% and 40% of the intramolecular interaction energy for the S-CH 3 and 68% for the S-CC thiol SAM, respectively. The latter has been calculated using the Au–S binding energy of 2.60 eV of alkyl chain thiols …”